Simply put, it’s to avoid a mayoral byelection. This is a quirk (if you’ll pardon the pun) of the local government electoral system, in which councillors can be appointed, rather than elected, within 12 months of a scheduled general election in the event of a sitting councillor resigning or otherwise leaving office.

He was installed as lord mayor in May 2003, following the resignation of popular lord mayor Jim Soorley.

Quinn went on to lose the lord mayoralty to the young upstart, “Can Do” Newman.

Another major factor in Quirk’s decision is a lot more personal.

To his credit, Quirk’s family has largely been kept out of the public spotlight. But it is widely known the long hours in City Hall hung heavily on his shoulders, as it meant spending valuable time away from his special-needs daughter.

So, what is Quirk’s legacy? Like all leaders, it could take some time for that question to be fully answered.

There’s his signature project, the Brisbane Metro, a new bus network that, while certainly worthwhile, does not live up to its “metro” moniker when compared with examples overseas.

His economic policies have reaped benefits and his push to host the Olympics – with its related transport infrastructure – could be an absolute game-changer for the city.

And he’s been a steady hand, liked (on a personal level, at least) by most who deal with him, even those from across the aisle.

But in the end, the happiest man in Brisbane right now is Rod Harding, who is again running for lord mayor.

You can almost hear the corks popping at Labor HQ.

The 2016 election showed how important Quirk was to the LNP. He outpolled Harding in several Labor wards, suggesting Labor-leaning voters were happy to split their vote between their local Labor candidate and an LNP lord mayor.

Without Quirk, Labor must surely see City Hall as theirs for the taking.